<mat-card style="margin-top: 60px">
    <div class="row justify-content-center">
        <div class="col-md-8">
            <div [hidden]="!errorMessage">
                <div class="alert alert-danger">{{errorMessage}}
                </div>
            </div>
            <br>
            <div [hidden]="!error403" class="alert alert-danger">
                未登录或登录已超时，请重新登录......
            </div>
        </div>
    </div>
</mat-card>
